DE69305847T2 - DEVICE AND METHOD FOR REMOVING POLLUTANTS FROM WASTEWATER - Google Patents

Abstract

The present invention provides a bioremediation process for pollutants. The present process utilizes an adsorbent coated biologically active support for use in biological remediation processes for pollutants, for example, in industrial and municipal waste waters and by-products, and to a bioreactor comprising the biologically active support.

Description

The present invention relates generally to a biological depollutant process. The present process utilizes a biologically active carrier coated with an adsorbent for use in biological depollutant processes, such as industrial and municipal wastewater and waste products, and a bioreactor containing the biologically active carrier.

There are already various chemical and biological processes for removing pollutants, of which biological removal is an effective and highly desirable approach. Generally speaking, depolluting microorganisms metabolize pollutants into simple chemical structures and sometimes even break them down completely, either in an aerobic process to carbon dioxide and water or in an anaerobic process to methane.

Various biological depollution processes are already known. For example, US-A-4 634 672 describes biologically active compositions for the purification of waste water and waste air, which contain a polyurethane hydrogel containing (i) surface-active carbon with a specific BET surface area of more than 50 m²/g, a polymer with cationic groups and enzymatically active and viable cells. US-A-4 681 852 describes a process for the biological purification of waste water and/or waste air, in which the water or the air is brought into contact with the biologically active composition according to US-A-4 634 672. The test examples cited in these patents show that this process cannot reduce the pollutant concentrations in the discharge stream to below 44 parts per million (ppm).

Rehm and his colleagues further refined the use of activated carbon in the aerobic oxidation of phenolic compounds by using microorganisms immobilized on granular carbon as a porous biomass carrier system. By taking advantage of the tendency of microorganisms to grow on a surface and remain bound to it, Rehm used granular activated carbon with a high surface area (1300 m²/g) as a carrier, to which cells were bound within its macropores and on its surface, as a porous biomass carrier system in a loop reactor for phenol removal; see HM Ehrhardt and HJ Rehm, Microbiol. Biotechnol., 21, 32-6 (1985). The resulting "immobilized" cells showed phenol tolerance up to a feed stream content of about 15 g/L, whereas free cells only tolerated up to 1.5 g/L. It was postulated that the activated carbon functions as a "buffer and storage facility" in protecting the immobilized microorganisms by absorbing toxic phenol concentrations and releasing only small amounts of the absorbed phenol for gradual biodegradation. This work could be improved somewhat by using a mixed culture immobilized on activated carbon [A. Morsen and HJ Rehm, Apl. Microbiol. Biotechnol., 26, 283-8 (1987)], where the researchers noted that a considerable amount of the microorganisms had "outgrown" into the aqueous medium, ie, considerable sludge formation occurred in their system.

It is known that the impregnation of flexible polymeric foams with activated carbon can increase the resistance of fabrics and clothing to the passage of harmful chemicals and gases, see for example US Patent Nos. 4,045,609 and 4,046,939. However, there is no mention of the use of these foams in wastewater treatment or of the fact that these foams represent a superior immobilization carrier for the growth and activity of microorganisms.

Givens and Sack, 42nd Purdue University Industrial Waste Conference Proceedings, pp. 93-102 (1987), conducted a detailed investigation of a carbon-impregnated polyurethane foam as a microbial carrier system for the aerobic removal of contaminants, including phenol. For this purpose, activated carbon-impregnated polyurethane foam was used internally in an activated sludge reactor. porous polyurethane foam with microorganisms externally bound to it was used. However, the process resulted in significant sludge formation, and the carbon had no beneficial effect.

H. Bettmann and H.J. Rehm, Appl. Microbial. Biotechnol., 22, 389-393 (1985), used a fluidized bed bioreactor for continuous aerobic phenol degradation, achieving a hydraulic residence time of about 15 hours, using Pseudomonas putida entrapped in a polyacrylamide hydrazide gel. The use of microorganisms entrapped in polyurethane foams for aerobic phenol oxidation in shake flasks has also been reported; see A.M. Anselmo et al., Biotechnology B.L., 7, 889-894 (1985). This appears to be the only report of the use of microorganisms entrapped in a foam for the biodegradation of organic pollutants.

However, known biological decontamination processes have a number of inherent disadvantages. For example, a significant consequence of the increased use of such processes is a constantly growing amount of sludge, which represents a serious disposal problem.

The use of anaerobic sewage treatment systems has been proposed to solve the sludge problem; see William J. Jewel, "Anaerobic Sewage Treatment," Environ. Sci. Technol., Vol. 21, No. 1 (1987). The main difference between aerobic and anaerobic systems is the cell yield. However, anaerobic systems can only degrade or metabolize a limited number of substrates; they cannot degrade or metabolize polynuclear aromatic hydrocarbons or unsubstituted aromatic hydrocarbons such as benzene, anthracene and phenanthrene, which are often present alongside phenol in industrial wastewater such as coal tar and coke processing wastewater (see Battersby, NS and Wilson, Valerie, "Survey of the Anaerobic Biodegradation Potential of Organic Chemicals in digesting Sludge", Applied and Environmental Microbiology, Vol. 55, No. 2, pp. 433-439 (February 1989), and JM Thomas, MD Lee, MJ Scott, and CH Ward, "Microbial Ecology of the Subsurface at an Abandoned Creosote Waste Site", Journal of Industrial Microbiology, Vol. 4, pp. 109-120 (1989)).

Another inherent disadvantage of some known biological removal processes is that these processes do not reduce the content of organic pollutants to reasonable levels, preferably below 0.1 parts per million (ppm), with reasonable residence times (preferably less than 24 hours), as already stated above.

The present invention relates to a biologically active carrier for removing pollutants from a fluid stream, comprising:

(a) a coated carrier made of a substrate with a coating composition applied thereto at least in places, containing (i) at least one particulate absorbent which absorbs and then releases the pollutants; (ii) at least one binder binding the absorbent to the surface of the substrate with a Tg below 100°C and optionally (iii) a zwitterionic or anionic suspending aid, the suspending aid having anionic functionalities selected from the group consisting of sulfonate, sulfate, sulfite, phosphate, phosphite, phosphonate, carboxylate and combinations thereof, and

(b) one or more pollutant-degrading microorganisms adhered to the surface of the coated carrier.

The present invention also relates to a process for purifying an aqueous feed stream containing pollutants, in which the feed stream is passed through a bioreactor in the presence of a gas containing an effective amount of oxygen, the bioreactor containing a biologically active carrier according to the above definition contains.

The present invention also relates to a process for producing the biologically active carrier, which comprises:

(a) applying a binder to the surface of a substrate,

(b) applying one or more particulate absorbents to the binder,

(c) allowing the binder to harden and

(d) adhering one or more microorganisms to the surface of the coated support, the binder binding the absorbent to the surface of the substrate and having a Tg below 100ºC, the absorbents being capable of absorbing the contaminants and the microorganisms being capable of degrading the contaminants.

The invention in another embodiment relates to a process for producing the biologically active carrier, in which:

(a) preparing a slurry containing at least a binder, one or more particulate absorbents, a zwitterionic or anionic suspending aid and a non-aromatic solvent,

(b) applying the slurry to the surface of a substrate to form a coated carrier,

(c) allowing the coated carrier to dry and

(d) adhering one or more microorganisms to the surface of the coated carrier, wherein the binder binds the absorbent to the surface of the substrate and has a Tg below 100°C, the absorbents are capable of absorbing the contaminants, the suspending aid has anionic functionalities selected from the group consisting of sulfonate, sulfate, sulfite, phosphate, phosphite, phosphonate, carboxylate and combinations thereof, and the microorganisms are capable of degrading the contaminants.

A deeper understanding and further benefits of Invention will become apparent from the following detailed description and the accompanying drawings, in which:

Figure 1 is a side cross-sectional view of a vertical reactor for use in a preferred embodiment of the invention;

Figure 2 is a side cross-sectional view of a horizontal reactor for use in the process according to the invention.

Figure 3 shows a cross-sectional view of a preferred biologically active particle for use in the method of the invention.

Figure 4 shows a diagram of a support having a coating layer with adsorbent dispersed in the coating.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

According to the invention, methods and apparatus for biological contaminant removal are provided. Embodiments of the present invention introduce purification processes that can significantly reduce contaminant levels in the effluent stream of a reactor, and often even keep them below the concentrations prescribed by the U.S. Environmental Protection Agency (EPA), despite occasional "shock loading" of the biological system by a relatively high contaminant level in the feed. "Shock loading" refers to a change in the contaminant concentration in the feed stream of about 500 to 5,000 parts per million over a relatively short period of time, usually in the range of 1 hour to 1-2 days. In order to obtain a purification process that is resistant to shock loading by relatively high contaminant levels in the feed stream, which is also often referred to as resistance to interference, the choice of biologically active carrier materials and the components used therein is important. One of the main objectives of the invention is to provide a carrier material having an effective amount of active adsorbent on a substrate for use in a biological waste treatment reactor, which achieves the legally required contaminant content in the discharge stream and is resistant to disturbances in the treatment system.

Many aspects of the present invention will be better understood by those skilled in the art by reference to the figures. In Figures 1 and 2, the numeral 10 designates a reactor for use in the process of the invention. A waste water stream containing one or more pollutants is fed into reactor 10 via inlet 12, passed through reactor 10 in the presence of a gas containing an effective amount of oxygen at a rate sufficient to reduce the concentration of at least one of the pollutants in the effluent stream to the desired level, and discharged from the reactor via outlet 14. Reactor 10 contains a plurality of biologically active carrier materials, represented in Figures 1 and 2 by the numeral 16. As shown in Figure 3, the biologically active carrier materials 16 include a carrier 18 with one or more types of particulate absorbents 20 for at least one of the pollutants contained in the aqueous stream. The absorbents are firmly bound to the surface of the substrate 18, in the micropores of the substrate 18 or both to the surface of the carrier 18 and in the micropores of the substrate 18 using a binding agent. The absorbents can be present not only on the surface of the substrate 18, but also next to it or instead inside the substrate material. Biologically active carrier materials 16 also contain on, in or on and in the substrate 18 and/or the absorbent 20 one or more types of microorganisms that can metabolize at least one of the substances contained in the waste stream.

In a process for cleaning a waste stream by biological degradation, the waste feed stream containing one or more contaminants is passed through a bioreactor which contains the biomass carriers and has generally been pretreated with microorganisms that degrade pollutants. The biomass carriers according to the invention are a carrier on which an effective amount of one or more microorganisms that degrade pollutants is located. The carriers are made biologically active by inoculation with microorganisms before use.

The substrate used in the practice of the present invention can vary in shape. The size and shape of the substrate can vary widely. For example, the substrate can be in the form of regular, such as tubular, rod-shaped, rectangular, spherical, hexagonal or the like, or even irregularly shaped particles. The substrate size can vary widely and is preferably at least about 0.25 cm to about 60 cm. Particularly preferred substrate sizes are about 0.25 cm to about 30 cm, most particularly preferred substrate sizes are about 1.3 cm to about 15 cm, with a particle size of about 1.3 cm to about 8 cm being the particle size of choice.

In the preferred embodiments of the present invention, the substrate is preferably an open cell material with relatively high macroporosity, such as a foam. This allows a contaminant-containing feed stream to flow through the interior of the substrate. In the preferred embodiments of the invention, the substrate voids are at least 0.2 millimeters and preferably about 0.2 mm to about 6 mm. The substrates must also be resistant to the shear forces and abrasion in a fixed bed reactor and should also have good compressive strength. In these preferred embodiments of the invention, the substrate 18 is preferably semi-flexible and has a density of less than about 2 pounds per cubic foot (32 kg/m³) for optimal economic viability. However, substrates with higher densities, from about 4 to about 5 pounds per cubic foot (64 to 80 kg/m³) or even more, are also contemplated. Note that the density of the substrate is related to the economics of the invention and not to its effectiveness; the invention may be practiced over a wide range of substrate densities, although certain ranges may offer distinct economic advantages.

The material used to form the substrate is not critical and can vary widely. The only requirements are that the material must not degrade when in contact with the binder, solvent, waste stream or microorganisms, that it has a certain affinity for the binder and/or adsorbent of choice and that the substrate does not interfere with the properties of the adsorbent and/or binder.

Suitable substances for producing the substrate include, for example, ceramics, synthetic borides, glasses and the like. Other examples of suitable substrate substances are synthetic and naturally occurring polymeric substances, such as polyamides such as nylon-6,6, nylon-4, nylon-6, nylon-10, nylon-12, nylon-6,10 and the like; polyesters such as polyethylene terephthalate, polybutylene terephthalate, poly-1,4-cyclohexanedimethylene terephthalate and the like; polyolefins such as polyethylene, polypropylene, poly-4-methylpentene, polystyrene and the like; vinyl polymers such as polyvinyl alcohol, polyvinyl methyl ether, polyvinyl methyl ketone, polyvinylpyrrolidone and the like; acrylic polymers such as polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyacrylamide, polymethacrylamide and the like. Further suitable polymeric substances for use in the production of the polymeric substrate are polyurethanes, such as those obtained from the reaction of (a) diisocyanates such as toluene diisocyanates, diphenylmethane diisocyanates, hexamethylene-1,6-diisocyanate, dicyclohexylmethane diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, 4,4'-diphenylisopropylidiene diisocyanate, 3,3'-dimethyl-4,4'-diphenyl diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, dianisidine diisocyanate, tolidine diisocyanate, hexamethylene diisocyanate, 4,4'-diisocyananodiphenylmethane and the like with (b) polyols such as glycerin, trimethylolpropane, 1,2,6-hexanetriol, methyl glycoside, pentaerythritol, sorbitol, sucrose, ethylene glycol, diethylene glycol and hydroxy-terminated polyesters. These polyesters can be prepared by direct esterification of dicarboxylic acid with an excess of di- or polyfunctional alcohol. Examples of the acids are polytetramethylene adipate, polyethylene adipate, poly-1,4-butylene adipate, poly-1,5-pentylene adipate, poly-1,3-butylene adipate, polyethylene succinate and poly-2,3-butylene succinate. Polyether polyols can also be used. The polyether polyols can be produced by reacting a compound with active hydrogen atoms (such as dialcohols, polyalcohols, diphenols, polyphenols, aliphatic diamines or polyamines and aromatic diamines or polyamines) with alkylene oxides such as styrene oxide, butylene oxide, propylene oxide, epichlorohydrin or mixtures of these alkylene oxides.

In the preferred embodiments of the present invention, the substrate is made from open-cell polyurethanes, such as cross-linked polymeric substances that can be foamed with a suitable blowing agent such as nitrogen, helium, carbon dioxide, azodicarbonamide and the like to form open-cell foams having the void properties described above. In these preferred embodiments of the invention, the substrate 18 can be made and foamed in the presence of the selected microorganism without adversely affecting the microorganism.

In the particularly preferred embodiments, the substrate is made of open-cell polyurethanes such as cross-linked polyurethanes. Such materials are commercially available or can be prepared by known processes. For example, such materials are obtainable by reacting isocyanate prepolymers with water, which optionally contains diamines or polyamines as chain extenders or crosslinkers, or by reacting a suitable polyol with a suitable diisocyanate or polycyanate. Suitable polyols include long-chain aliphatic diols and polyoxyalkylene ethers. The isocyanate prepolymers have isocyanate end groups and are prepared by reacting polyoxyalkylene ethers with an excess of diisocyanate or polyisocyanates. Suitable polyoxyalkylene ethers are, for example, those with a molecular weight of about 500 to about 10,000, preferably about 2,000 to 8,000, at least two active hydrogen atoms and at least 30% by weight, based on the total weight of the polyether, of oxyethylene groups. Other suitable oxyalkylene groups include oxypropylene, oxybutylene and the like. Polyethers of this type are prepared by reacting compounds having reactive hydrogen atoms such as dialcohols, polyalcohols, diphenols, polyphenols, aliphatic diamines, aliphatic polyamines, aromatic diamines or aromatic polyamines with a suitable alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide and the like. Suitable diisocyanates include toluene-4,4'-diisocyanate, toluene-2,4-diisocyanate, toluene-2,2-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-2,2'-diisocyanate, toluene-2,6-diisocyanate, hexamethylene-1,6-diisocyanate, and diamines and polyamines include aliphatic, cycloaliphatic and aromatic di- and polyamines such as ethylenediamine, hexamethylenediamine, diethylenetriamine, hydrazine, guanidine, carbonate, N,N'-diisopropylhexamethylenediamine, 1,3-bisaminomethylbenzene, N,N'-bis-(2-aminopropyl)-ethylenediamine, N,N'-(2-aminoethyl)-ethylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-dimethylamino-3,3'-dimethyldiphenylmethane, 2,4'-diaminodiphenylmethane, 2,4-diaminotoluene, 2,6-diaminotoluene and the like.

The amount of substrate used in the carriers (measured in the absence of any microorganisms) can vary widely. Generally, the amount of substrate is from about 10 to about 70 weight percent, based on the total weight of the biologically active carrier. In the preferred embodiments of the invention, the amount of substrate is from about 20 to about 60 weight percent, based on the total weight of the carrier, and in the most preferred embodiments, from about 30 to about 50 weight percent, based on the above basis.

In the present invention, the polymeric substrate material is most preferably a flexible, open-cell foam with high water permeability. The foam used in the practice of the present invention must be able to accommodate the feed stream in a reactor. To this end, it is important that the foam has a highly cross-linked pore structure, with the foam cavities suitably being at least about 0.2 millimeters in size and can be up to 10 millimeters or more in size.

The adsorbent for use in carrying out the present invention can vary widely. Examples of substances suitable for use in the preparation of adsorbents are carbons such as coal, soot, activated carbon, silica gel, active clays, zeolites, hydrophobic and ion exchange resins, molecular sieves and the like. In the preferred embodiments of the invention, the adsorbent is prepared from carbons such as coal, charcoal, soot and activated carbon and in the particularly preferred embodiments of the invention, the particulate adsorbent is prepared from activated carbon. However, it is obvious to those skilled in the art that any other particulate material can also be used to prepare an adsorbent. The activated carbon which is preferably used can be prepared by heat treatment of plant and animal substances, coal, also brown coal, petroleum residues or synthetic organic polymers, possibly with the addition of chemicals, and is characterized by rapid and effective absorption of the target pollutants.

The adsorbent, e.g. activated carbon, should act as a solid phase buffer after binding to the substrate, which absorbs excess pollutant in the reactor when the pollutant concentration increases and releases pollutant into the solution when the concentration decreases. The buffer effect is described by a series of uptake and release constants (Kauf and Kab), each of which represents the affinity of a specific location on the adsorbent to a specific pollutant. The ratio kab/kauf corresponds to the constant KD, which represents the affinity of the adsorbent to a pollutant. In equilibrium, the number of pollutant molecules that are bound to the adsorbent corresponds to the number of pollutant molecules that leave the adsorbent and go into solution. In the process according to the invention, the adsorbent basically has a bound phase after binding to the substrate or the substrate and the binder or the binder which is in equilibrium with the solution sufficiently quickly so that pollutants in solution which result from an increase in the pollutant concentration in the feed stream for a duration of 1 hydraulic retention time (HRT) are bound within a fraction of this HRT, preferably about 1/24 HRT, after the increase has ended and a desired pollutant content is maintained in the discharge stream. However, the pollutant should also be released into the solution so quickly that the pollutant can be microbially degraded after returning to a concentration which is equal to or lower than the initial concentration of the pollutants in the feed stream (C₁). The desired pollutant content in the waste stream per day or per month is normally prescribed by legal requirements. The desired pollutant content in the discharge stream also determines the amount of pollutant in a treatment process for absorbing an increased amount of pollutant in the waste stream. The settling time should generally be at least less than about 1 HTZ. In other words, for a feed stream having a contaminant concentration C2 above the contaminant concentration (c1) of a first feed stream flowing through a reactor over a period of 1 HTZ, e.g. 24 hours, the carrier media should be capable of absorbing a significant portion of the excess contaminant in the reactor (and, in conjunction with the degradation action of the microbes, returning the contaminant concentration in the effluent stream to the level prior to the increase to C2) within at least 24 hours after the end of that 1 HTZ at the higher contaminant concentration. The settling time is preferably less than or equal to 1/3 HTZ, and more preferably less than or equal to 1/6 HTZ. In particularly preferred embodiments, the settling time is less than or equal to 1/8 HTZ. In particularly preferred embodiments, the settling time is less than 1/12 HVZ and most preferably less than or equal to 1/24 HVZ.

The adsorbent is in particulate form and is preferably porous to provide a larger surface area. The preferred particulate adsorbent has a surface area of at least 500 m²/g, preferably at least 700 m²/g, and is preferably sized such that 70% of the adsorbent particles are smaller than 44 µm, ie at least 70% of the adsorbent particles pass through a sieve with a mesh size of 44 µm (325 mesh). In the preferred embodiments of the invention, the powdered adsorbent has as high a pore volume as possible, more preferably at least 0.5 cm³/g and most preferably at least 0.7 cm³/g, with as high a porosity as possible, to which pores with a size of over 1 µm preferably contribute. Powdered adsorbent used in the practice of the preferred embodiments of the present invention has a surface area of 700 to 2000 m²/g and a pore volume of 0.7 to 1.0 cm³/g, with 70 to 100% of the particles being smaller than 44 µm. Although these values correspond to the properties of commercially available material, there are no such restrictions in the invention per se, so that materials with the highest possible surface area are the materials of choice.

The amount of adsorbent to be used can vary widely and depends on a number of factors, including the specific activity of the adsorbent with respect to the target pollutant. In the preferred embodiments of the invention, the amount of adsorbent is sufficient to at least maintain a steady state level of such a target pollutant that the microorganism can metabolize the pollutant within the time required to provide an effluent stream containing less than 22 ppm of target pollutants. In the most preferred embodiments of the invention, the amount of adsorbent is from about 5% to about 85% by weight on a dry solids basis based on the total weight of substrate, binder and adsorbent. In the most preferred embodiments of the invention, the amount of adsorbent is from about 10% to about 50% by weight on a dry solids basis based on the total weight of substrate, binder and adsorbent. In the most preferred embodiments of the invention, the amount of adsorbent is from about 15% to about 35% by weight, based on the above basis.

There are various methods for applying an adsorbent to the substrate. Some of these involve various bonding processes, such as heat treatment, solvent slurries and bonding to the binder. Alternatively, the absorbents can be added to the substrate precursor composition to produce absorbent-filled substrates. The heat treatment process involves heating a substrate to a temperature at which it softens, adding carbon and then allowing the substrate material to cool. Upon cooling, the Adsorbents are applied or attached to the substrate surface. The temperatures and heating times vary depending on the choice of substrate and adsorbent. A largely single-phase adsorbent particle layer is formed on the surface of the carrier produced by the heat treatment process.

A solvent-absorbent slurry may also be used to apply the substrate using conventional methods. The substrate is immersed in the slurry or spray coated with the slurry and then dried. It is important that the adsorbent is securely attached to the substrate in an active state after any excess slurry and solvent have been removed from the carrier. Note that although the process is referred to as a "solvent slurry," the solvent only serves as a carrier for dispersing the adsorbent in a fluid matrix or may soften the substrate surface and/or cause the substrate to swell. After the slurry is coated on the substrate, the solvent can be evaporated and reused. Just like the heat treatment process, the solvent slurry process also results in a single-phase adsorbent particle layer on the surface of the support because the solvent is largely removed by conventional drying methods.

Other suitable methods for adsorbent bonding using binders are generally of two types, namely a slurry method and a "two-step method". In the "two-step method" (i) a layer of binder is applied to the surface of a substrate and curing is allowed to begin, (ii) one or more adsorbents are added to the binder-substrate surface, and (iii) the binder is allowed to fully cure. The two-step method may be due to the need of two curing steps prove to be economically uninteresting. In this respect, the main focus of the present invention is on the application of an adsorbent to a substrate by means of a simplified coating treatment. In the process according to the invention, a slurry layer containing a binder, an adsorbent and solvent is applied and the slurry layer is allowed to dry. The slurry process makes it possible to dispense with intermediate drying steps and thus to manufacture the carriers in large batches.

The choice of binder can vary greatly. An effective binder is a material that can bind an adsorbent to the surface of a substrate in such a way that no or practically no adsorbent is lost in the bioreactor output and the adsorbent is practically not deactivated by the binder. In particular, an effective binder is selected so that the cleaning process is resistant to interferences. As long as the process remains resistant to interferences, even a partial coating of the carrier is acceptable. The binder can be selected from all types of binder known, for example, in particle, pigment or powder binding technology. Examples of binders include water-suspensive polymers such as those found in latex formulations and water-soluble polymers that can be deposited, crosslinked or polymerized into water-insoluble forms, such as natural gums, cellulose and starch derivatives, alginic acid salts and polymers and copolymers of acrylic acid, acrylamide, vinyl alcohol and vinyl pyrrolidone. Examples of suitable organic binders that are soluble in organic solvents include cellulose esters, cellulose ethers, polymers and copolymers of vinyl esters such as vinyl acetate, acrylic acid esters and methacrylic acid esters, vinyl monomers such as styrene, acrylonitrile and acrylamide and dienes such as butadiene and chloroprene, natural rubber and synthetic rubber such as styrene-butadiene.

Binders tend to reduce the performance of an adsorbent by reducing the capacity of the adsorbent or by impeding access of a contaminant to the adsorbent, for example when the binder envelops the adsorbent. It is believed that the disadvantages associated with an adsorbent-binder-support system can be at least partially compensated by the use of binders with a larger free volume. Applying binder and adsorbent from a slurry results in a coated support consisting of a substrate with an adsorbent dispersed in or in and on the coating layer (see Figure 4). Since the slurry method results in the second matrix layer in which the adsorbent is dispersed in a binder, the binder can often envelop the adsorbent. To this end, the preferred embodiments use binders that have a larger free volume so that a significant portion of the activity of the adsorbent is retained and enough interaction between the pollutant and the adsorbent can take place so that when the carrier is used in a bioreactor, the purification process is resistant to interference. Free volume (vf) refers to the fluidity and mobility of the polymer chains and is a measure of the volume through which small molecules can migrate. The free volume is the difference between the specific volume of the polymer mass (v) and the volume of the densely packed molecules. Basically, the free volume of the entire polymer is the volume of the polymer mass that is not occupied by the molecules themselves.

It is currently known that the glass transition temperature Tg correlates with the free volume. A discussion of free volume and Tg can be found in Stephen L. Rosen, Fundamental Principles of Polymeric Materials, Chapter 8, "Transitions in Polymers", pp. 89-95, 1982. Rosen theorizes that Tg decreases with increasing free volume in a polymer. As such, Tg is used to relate the structure of the binder to its ability to function as an effective binder in a biomass support system. The binder of the invention has a Tg below 100°C. In particularly preferred embodiments, the effective binder has a Tg less than or equal to 50°C. In further preferred embodiments, an effective binder has a Tg less than or equal to 30°C. In most preferred embodiments, an effective binder has a Tg less than or equal to 20°C. In most preferred embodiments, an effective binder has a Tg less than or equal to 0°C. In alternative embodiments, the preferred binder has a Tg less than or equal to 10°C, with the binder of choice having a Tg less than or equal to 25°C.

As noted above, the affinity of the carrier for contaminants such as phenolic materials is related to Tg. In many cases, Tg can be lowered by increasing the polarity and/or hydrophilicity of the polymeric binder used in the carrier system. To improve such properties of a binder material, any conventional method for increasing the hydrophilicity or polarity of a polymer can be used. For example, many polymers, including homopolymers and copolymers, can be made more hydrophilic and/or polar by (1) carboxylation along the polymer backbone (e.g., carboxylated styrene-butadiene), by carboxylation of side chains and functional groups, and (3) by introducing -COOH group-containing monomers as comonomers in the polymeric binder. Any of the foregoing measures should lower the Tg of polymers.

An effective binder is so well suspended or dispersible in solvent that the mixture obtained after mixing the binder and the solvent is a stable dispersion of the binder which can be applied to a substrate to produce a relatively uniform coating. In a preferred embodiment, the binder should be soluble in a non-aromatic solvent if a solvent is required, since an aromatic solvent can deactivate some adsorbents. After application and curing of the coating composition, the binder should be substantially water-insoluble for use in a waste stream treatment process and should not degrade in the bioreactor environment. The binder should also not unduly impair the ability of the adsorbent to bind contaminants. Many commercial binders, e.g. adhesives, are manufactured and sold in the form of dispersions. In preferred embodiments, the binder is water-suspensive for application to the substrate and is water-insoluble after curing on a substrate. Examples of solvent-suspensive binders include those known in the art as latex. A latex is generally a solvent-suspensive form (liquid in liquid) stabilized by surfactants.

The amount of binder used in the practice of the invention will vary depending on the amount and structure of the substrate and the amount of adsorbent to be bound. The amount should generally be sufficient to both substantially cover the substrate and substantially bind the adsorbent. It should be noted that excess binder can not only significantly reduce the actual size of the internal pores of a substrate, but can also require additional amounts of additives to form an acceptable slurry. In addition, a thicker layer of binder surrounding the adsorbent tends to inhibit or impair the pollutant binding properties of the adsorbent. The presence of excess Additives such as surfactants can lead to the deactivation of an adsorbent.

The solvent used in preparing the coating composition contains a portion of water and a portion of organic solvent which puts the binder into a miscible or suspendable form to form the slurry coating. The choice of solvent can generally vary widely. The solvent can be selected from water, organic solvents, or mixtures thereof from 100% water to 100% organic solvent. Examples of organic solvents for use in the practice of the present invention include alcohols, esters, ethers, ketones, amines, and nitrated or halogenated hydrocarbons. Solvents that can be used in the practice of the present invention include water, alcohols such as methanol, ethanol, propanol, isopropanol, and ethylene glycol; Ketones such as acetone, methyl ethyl ketone, cyclohexanone and butyrolactone as well as acetic acid esters such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate. Also suitable are nitromethane, nitroethane, tetrachloroethane, chloroform, benzene, toluene, chlorobenzene, xylene, n-butyl chloride, cyclohexane, ethylene carbonate, propylene carbonate, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, acetonitrile, hexamethylphosphoramide, n-methylpyrrolidone, tetrahydrofuran, diethyl ether, formic acid and their derivatives.

The solvent used is preferably a non-aromatic solvent. Aromatic solvents tend to limit the amount of phenol bound by the adsorbent, particularly in the case of the treatment of aromatic pollutants such as phenols.

One of the novel features of the biologically active carriers according to the invention is the uniform distribution of the adsorbent in an active state on the surface of the substrate. To obtain such a uniform distribution, it is important to use an effective suspending aid when applying a slurry coating to a substrate to avoid the formation of large agglomerations of the adsorbent and the binding agent (clumping). Such agglomerations reduce or impair the diffusion of contaminants to and from the adsorbent, e.g. activated carbon. A suspending aid is used which has the least possible inhibitory effect on the ability of the adsorbent to bind contaminants and allows the formation of a suspension of the adsorbent in the coating composition which, when applied to the substrate, results in a uniform distribution of the adsorbent on the surface of the substrate.

The suspension aid is usually a salt of an organic substance. The cationic part of the salt can vary greatly. For example, it can be a protonated amine, i.e. an ammonium group, or an alkali metal. The suspension aid can be a zwitterionic or anionic substance. If the suspension aid is zwitterionic, the net charge is preferably not positive and particularly preferably negative. The suspension aid can be a compound or a polymer. Polymers can be advantageous because they have numerous sites for anionic groups along the main chain. Any functional group that gives the polymer compound an anionic character, i.e. a negative net charge, can be used. Functional groups include in particular sulfonates, sulfates, sulfites, phosphates, phosphites, phosphonates, carboxylates or combinations thereof. A cationic part is associated with these functional groups, resulting in a salt. In further preferred embodiments, the suspending aid is a surfactant or a surfactant-like material with a negative net charge and a hydrophobic part. Conventional, well-known surfactants can be used as suspending aids and dispersants.

In further preferred embodiments of the invention, the suspending aid is an anionic surfactant. In particularly preferred embodiments, the suspending aid is a dianionic organic compound or a dianionic organic polymer in salt form, as described above. In alternatively preferred embodiments, the suspending aid is a polyanionic substance. In preferred embodiments, the functional groups of the dianionic or polyanionic suspending aids are carboxylates, sulfonates, sulfates, phosphates or combinations thereof. In further preferred embodiments, the functional groups of the dianionic or polyanionic suspending aids are sulfonates, phosphates or combinations thereof.

Compounds from which a salt can be derived for the purpose of forming a suspending aid are represented by the following formulas:

where X is a functional group that imparts a negative net charge to the substance according to the formula,

R is a hydrocarbon such as aromatic, heteroaromatic, cycloaliphatic, aliphatic, and also hydrocarbons containing heteroatoms, as well as a peptide or a protein or a polymeric form of one of the above-mentioned groups,

U is a heteroatom, where the radicals not Bonds with R or X saturated valences are saturated with H, OH, halogen or a lower alkyl or alkoxy radical (ie 1-8 carbons).

n is such a whole number that the number of carbon atoms in the suspension aid is 1 to about 50. Here, n is preferably a whole number from about 5 to 25.

Suspending aids are commercially available surfactants or dispersants such as fatty acid salts, e.g. fatty acid sulfonates, alpha-olefin sulfonates, naphthalene sulfonates, biphenyl sulfonates and alcohol sulfonates or the corresponding phosphate counterparts of these sulfonates. Aromatic sulfonates and phosphonates or their esters are often used. In other embodiments, polyanionic polypeptides such as sodium caseinate are preferred.

The amount of suspension aid used varies depending on the concentration of the binder and the adsorbent in the coating composition. It should be noted that if too little suspension aid is used, agglomeration of the adsorbent occurs, which negatively affects the performance of the carrier formed from it and reduces the economic possibilities of the carrier production process. It can be seen from the examples that an excess of suspension aid can reduce the ability of the adsorbent to bind pollutants.

It is preferred to use an amount of suspending aid that is effective to obtain the best possible performance of the support system. An effective amount of suspending aid is that amount that is sufficient to provide a uniform distribution of the adsorbent on the surface of the substrate when the coating is applied, which amount does not substantially limit the binding capacity of the adsorbent to a level below that desired in view of the potential performance of the adsorbent in the presence of the selected suspending aid.

The possible concentration ranges of the suspending aid in the coating composition vary depending on the amount of the other components in the coating composition. For example, increasing the amount of water may allow less suspending aid to be used in the coating; however, the amount of binder used may require the use of more suspending aid. The effective amount can be determined by constructing one or more dose curves, varying the amount of suspending aid while keeping the amounts of the other components constant, and observing the clumping of the adsorbent on the substrate surface and the impairment of the ability of the absorbent to bind a desired contaminant.

Other ingredients may be added to the slurry to keep the components of the slurry in suspension during application of the slurry to a substrate. This is because the adsorbent suspended in the slurry may tend to settle out of the slurry. In such cases, an additive to prevent such settling, a so-called anti-settling agent, is advantageous. In a preferred embodiment, an anti-settling agent such as a viscosity improver, a thickener or a thixotropic agent may be used to prevent settling. In particularly preferred embodiments, the anti-settling agent is a polysaccharide. In further preferred embodiments, the anti-settling agent is an anionic polysaccharide. Examples of anti-settling agents for use in the practice of the invention include guar gum, carrageenan, locust bean gum, agar, algin, gum arabic, ghatti gum, tragacanth gum, karaya gum, pectin, xanthan gum, tamarind gum, psyllium seed gum, quince gum, larch gum, and cellulose thickeners such as carboxymethylcellulose and carboxy-2-hydroxyethylcellulose. The cellulose thickeners are preferred. Carboxymethylcellulose is particularly preferred.

Biologically active carriers may contain various optional ingredients. Examples of other optional components that may be used in the practice of the present invention are density-increasing substances such as barite, metal powder, rubber powder, clay powder, pumice powder, glass powder, powders obtained from the pits and shells of olives and nuts, and rock flour; density-reducing substances such as small polystyrene beads, wood powder, powder from plastic waste, micro-hollow beads and polyethylene foam flakes; colorants such as coloring pigments and dyes; short fibers of organic or inorganic basis such as glass fibers and gel-forming macromolecular substances such as cellulose types, alginates, starch and carrageenans.

After the adsorbent has been bonded to the carrier, the biomass carrier produced in this way is cut to a suitable size as required and filled into a reactor. Alternatively, the substrate can also be coated on particles of the size to be used in a bioreactor. A suspension of pollutant-degrading microbes is then fed into the reactor. The microbes capable of biological degradation are absorbed and bound on, in or on and in the porous carriers by well-known natural processes.

It is assumed that the ability of a carrier to implement the method according to the invention, which, as already explained above, is resistant to interference, is related to the alpha value of the specific carrier. The calculation of an alpha value is carried out according to the following formula:

Alpha value = [g pollutant removed from the solution]

[g carrier]

/[g pollutant remaining in solution]

(g of the pollutant solvent]

The alpha value represents the ability of the carrier (per g) to remove a contaminant from the solution. The alpha value is determined using a fixed amount of a particular contaminant in water or another solvent for the contaminant (100 ppm contaminant in 100 mL solution) by measuring the initial concentration of the contaminant and the final concentration of the contaminant after the carrier has been placed in the solution for a fixed period of time, usually about 24 hours.

By measuring the pollutant concentration in the solution after 24 hours, an alpha value for the carrier is obtained. In the process according to the invention, the carrier used should have an alpha value (per gram of carrier, the carrier containing a substrate, an adsorbent and optionally a binder) of at least about 100. The alpha value for the carrier is preferably at least about 200 and more preferably at least about 400. In further preferred embodiments, the alpha value is at least about 600. In particularly preferred embodiments, the alpha value is at least about 1,000. In very particularly preferred embodiments, the alpha value is at least 1,500. In alternative embodiments, the alpha value is at least about 2,000, with the alpha value of choice being above about 3,000.

The microorganisms used in the practice of the present invention are anaerobic or aerobic microorganisms selected to degrade target pollutants in a manner well known in the art. The microorganisms may be used as a pure strain or as a collection of microorganisms. In preferred embodiments of the invention, aerobic microorganisms are used. Although anaerobic microorganisms often degrade pollutants at a slower rate than aerobic microorganisms, an anaerobic process may be required to degrade a pollutant or intermediate to a substance that can be aerobically degraded to a nontoxic level or to a harmless substance. For example, ammonia may be degraded anaerobically and then aerobically to the final products. Suitable microorganisms, which can vary widely, may be naturally occurring microorganisms or genetically engineered microorganisms. The only requirement is that the microorganisms are able to metabolize the target pollutant(s) for the required period of time to the required output levels. In the preferred embodiments of the invention, the microorganisms are obtained from the pollutant-containing waste stream or from soil that has been in contact with the waste stream.

When carrying out the process, the cell content of microorganisms, including the extracellular proteins produced by microorganisms, is so high that it is sufficient to reduce the content of organic pollutants to the desired concentration within the desired hydraulic residence time. In the preferred embodiments of the invention, the cell content of microorganisms is at least about 0.3% by weight, based on the total weight of microorganisms, substrate, binder and adsorbent, and in the most preferred embodiments of the invention from about 0.3% by weight to about 15% by weight, based on the above-mentioned basis. Among these most preferred embodiments, those embodiments are most preferred in which the cell content of microorganisms 22 is about 0.5 to about 10% by weight based on the total weight of adsorbent, microorganisms and substrate, with the content of choice being about 0.8 to about 5% by weight based on the above basis.

Although biological treatment can be carried out using aerobic or anaerobic microorganisms, aerobic processes are preferred because aerobic systems work faster than anaerobic ones. The process takes place in the presence of a gas that contains an effective amount of oxygen. An "effective amount of oxygen" is defined here as a The term "oxygen supply" is understood to mean the amount of oxygen sufficient to supply the oxygen required by the microorganisms to metabolize the target pollutant. It is important that the reactor 10 be supplied with the amount of oxygen necessary for proper microbial metabolism and pollutant degradation. The amount of oxygen required in any given situation varies widely and depends to a considerable extent on the requirements of the microorganisms employed in the process and other factors known to those skilled in the art. Generally, the amount of oxygen distributed in the process feed stream is at least about 2 mg of oxygen per liter of aqueous feed. In the preferred embodiments of the invention, the amount of oxygen is from about 2 mg/L of feed to about 10 mg/L of feed, and in the most preferred embodiments of the invention, from about 6 mg/L of feed to about 8 mg/L of feed. In the preferred embodiments of the present invention, the gas is distributed uniformly or substantially uniformly throughout all or only a portion of the biologically active biomass. The manner in which the gas is fed to the reactor 10 can vary widely. The gas may be introduced into the reactor 10 by conventional methods. For example, in a vertical or upflow reactor 10 as shown in Figure 1, the gas is introduced along with the aqueous feed stream at the bottom of the reactor 10 using the sparger 24 which introduces the gas in the form of small diameter gas bubbles. Additional gas may optionally be introduced at various points along the vertical of the reactor 10 (not shown in the drawing). In an embodiment of the invention in which the reactor 10 is a horizontal reactor such as that shown in Figure 2, the gas may be introduced at various points along the horizontal of the reactor 10 to achieve a substantially uniform distribution of the gas in the feed stream in the reactor 10. In this embodiment, the upflow flowing gas perpendicular or substantially perpendicular to the flow direction of the aqueous feed stream. In the most preferred embodiments of the invention, the reactor 10 has a horizontal configuration in which the gas is distributed uniformly or substantially uniformly throughout or substantially throughout the reactor 10. In these most preferred embodiments, the gas is fed to the reactor 10 along its horizontal, as shown in Figure 2. This procedure achieves a more uniform distribution of the gas in the feed stream.

Process temperatures can vary widely and depend on the specific microorganisms selected for use. In general, the process is carried out at a temperature that is high enough not to unduly disturb the metabolism of the microorganism and low enough not to deactivate the microorganism by heat. Process temperatures are generally from about 5ºC to about 65ºC, preferably in the range of about 15ºC to about 65ºC, more preferably in the range of about 12ºC to about 45ºC, and most preferably in the range of about 25ºC to about 35ºC.

In the process according to the invention, the aqueous pollutant-containing stream is treated for a period of time which is sufficient to reduce the concentration of at least one pollutant in the effluent stream to the desired extent. In general, for aqueous feed streams in which the concentration of at least one pollutant is less than or equal to about 5,000 ppm, a hydraulic residence time of less than about 48 hours, preferably less than about 24 hours, and more preferably less than about 15 hours, is sufficient to reduce the concentration of at least one pollutant in the effluent stream to a concentration of less than or equal to about 22 parts per million (ppm), preferably less than or equal to about 10 ppm, more preferably less than or equal to about 1 ppm, and most preferably less than or equal to about 0.1 ppm, with the concentration of choice being less than or equal to about 0.02 ppm. The respective hydraulic residence time depends on the amount of contaminants in the feedstock, the operating temperature, the presence of other materials in the feedstock, the density of microorganisms in the fixed bed, etc.

The aqueous waste streams which can be treated using reactors containing the biomass carriers of the invention and the pollutants contained in such streams can vary widely. Waste streams containing inorganic (e.g. ammonia) or organic materials can be treated. Organic materials include a wide range of hydrocarbons and modified hydrocarbons such as aliphatics, aromatics, heteroaromatics and their halogenated derivatives. Organic pollutants also include hydrocarbons containing functional groups such as hydroxy, aldehyde, carboxylic acid, cyano, phosphorus and sulfur-containing groups (-SO₃H, -SO₄, -S-, SH and -SR, where R is a monovalent hydrocarbon). One of the most important classes of organic pollutants consists of aromatic hydrocarbons such as benzene, toluene, xylenes, alkylbenzenes, phenolic substances and their halogenated derivatives and polynuclear aromatic hydrocarbons such as naphthalene, anthracene, chrysene, acenaphthylene, acenaphthene, phenanthrene, fluorene, fluoranthene, naphthacene, pyrene and their halogenated derivatives (e.g. polychlorinated biphenyls, hexachlorobenzene, 5-bromouracil, 2,4-dichlorophenol, etc.). In the preferred embodiments of the present invention, the pollutants are those which are frequently found in waste streams from industrial production facilities. For example, phenolic substances are preferred for treatment in the process according to the invention. Examples of phenolic substances are phenol, cresols, resorcinol, catechol, halogenated phenols such as 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2,-4-dichlorophenol, pentachlorophenol, nitrophenols such as 2-nitrophenol and 4-nitrophenol and 2,4- Dimethylphenol. Phenolic substances are found in waste streams from phenol producers, phenol consumers, phenol resin producers, coal tar processing plants and pulp plants and other delignification plants. However, this does not mean that the process can or must only be carried out with such streams. The process according to the invention can be carried out with any aqueous feed that contains levels of organic pollutants to be reduced. The pollutants in the treated waste streams are preferably non-particulate substances.

The initial concentration of the pollutants contained in the aqueous waste stream used in the process according to the invention can vary greatly. One of the advantages of the present invention compared to already known biological removal processes is that waste streams with a relatively high pollutant content can also be treated. The concentration of organic pollutants in process streams that can be treated according to the process according to the invention are "biologically treatable levels". "biologically treatable levels" are understood here to mean pollutant concentrations that do not or do not excessively inhibit the metabolism of the pollutants by the microorganism. Discharge streams from industrial processes, such as phenol production plants and coal tar processing plants, can have pollutant levels above 20,000 ppm, which can interfere with the process. It is preferred to reduce these levels to a biologically treatable level by conventional methods such as solvent extraction, steam distillation and the like. The concentration of pollutants in the aqueous streams is generally less than or equal to about 5000 ppm. The lower concentration is obviously not critical and does not represent a limitation of the process. In the preferred embodiments of the present invention, the concentration of organic pollutants less than or equal to about 4000 ppm and in the particularly preferred embodiments of the invention less than or equal to about 3000 ppm. Among these particularly preferred embodiments of the invention, those are particularly preferred in which the pollutant concentration is less than or equal to about 2000 ppm, with the pollutant concentration of choice being less than or equal to about 800 ppm. With a longer hydraulic residence time, the treatment of higher pollutant concentrations is obviously possible.

For optimal biodegradation, it may be necessary to adjust the pH of the contaminant-containing feed. The pH is generally in the pH range at which the target contaminant(s) can be metabolized. In the preferred embodiments of the invention, the pH of the feed is from about 6 to about 9, and in the most preferred embodiment of the invention, the pH is from about 6.5 to about 7.5.

It may also be necessary to add nutrients. The supply of such substances can be achieved by using known additives such as fish meal peptone, soy meal, peanut oil, cottonseed oil and the like, whereby salts that can provide phosphate, sodium, potassium, ammonium, calcium, sulfate, chloride, bromide, nitrate, carbonate ions or similar ions may also be required. If necessary, trace elements known to the expert can be added. In aqueous use, sufficient quantities are often already present to meet the minimum requirements of the microorganism.

The aqueous feed stream is fed to the reactor 10 by conventional means and passed through it using an "effective hydraulic residence time". By "effective hydraulic residence time" is meant here a time sufficient to reduce the concentration of contaminants in the effluent stream to the desired level in accordance with the process. The hydraulic residence times can vary widely and are generally dependent on such factors such as the pollutant concentration in the aqueous feed stream, the desired maximum pollutant concentration in the aqueous discharge stream, the microorganisms contained in the biomass, the pollutant and the like. An advantage of the process according to the invention is that the pollutant concentration can be reduced within relatively short hydraulic residence times. In the preferred embodiments of the present invention, the hydraulic residence times are less than or equal to about 48 hours, and in the particularly preferred embodiments of the invention they are about 10 to about 36 hours. Among these particularly preferred embodiments, those in which the hydraulic residence time is about 10 to about 24 hours are very particularly preferred.

As already noted, an advantage of the process according to the invention is that it is resistant to interference from relatively high pollutant concentrations in the feed stream. If the concentration of a pollutant in a feed stream increases from a first concentration C₁ to a second, higher concentration C₂ for a period of 1 HVZ, the increase to c₂ causes an increase in the concentration of the effluent stream. In the present process, after passing a feed stream having the concentration C₂ through a reactor for a period of 1 HVZ, the concentration of the pollutant in the effluent stream is reduced to below about 0.15 C₂ within about 1/24 HVZ or faster. In addition, the process ensures that the pollutant concentration in the effluent stream decreases to C₁ and the pollutant concentration is maintained at about C₁. for the duration of at least one HVZ within 1 HVZ or faster to a value less than or equal to about 0.12 C₁. If the pollutant concentration is doubled from c₁ to C₂, where c₁ is a pollutant concentration which is below the concentration at which inhibition of the microorganisms occurs, the pollutant concentration in the discharge stream can be reduced, for example, using the treatment process to below 0.15 c₂ within 1/24 of the HVZ selected for the process. The process preferably enables a reduction of the pollutant concentration to concentrations c₂ at which the microorganisms would otherwise be at least partially inhibited.

In further embodiments of the present invention, the cleaning process is such that the pollutant concentration in the discharge stream after an increase in the pollutant concentration in the feed from C₁ to C₂ for a period of 1 HVZ within about 1/24 HVZ after the end of this 1 HVZ at C₂ is reduced to a maximum of about 0.075 C₂ and after the pollutant content in the feed returns to C₁ and C₁ is maintained for a period of at least 1 HVZ within 1 HVZ or faster to a maximum of 0.001 C₁.

Preferably, the pollutant concentration in the discharge stream in the cleaning process according to the invention is reduced after an increase in the pollutant concentration in the feed stream from C₁ to C₂ for a period of 1 HVZ within 1/24 HVZ after the end of this 1 HVZ at C₂ to a maximum of 0.01 C₂ and after the pollutant content in the feed stream has fallen again from C₂ to C₁ and C₁ is maintained for a period of at least 1 HVZ within 1 HVZ or faster to a maximum of 0.001 C₁.

In further preferred embodiments of the inventive cleaning process, the concentration of pollutants in the discharge stream is reduced after an increase in the concentration of pollutants in the feed from C₁ to C₂ for a duration of 1 HVZ within 1/24 HVZ after the end of this 1 HVZ at C₂ to a maximum of 0.005 C₂ and after the concentration of pollutants in the feed drops again from C₂ to C₁ and is maintained at or approximately at C₁ for a duration of at least 1 HVZ within 1 HVZ or faster to a maximum of 0.0005 C₁.

The novel biomass carriers according to the invention can be used in conventional biological waste treatment systems, such as in continuous stirred tanks, fixed bed reactors and fluidized bed reactors. In the practice of the present invention, it is preferred to use a fixed bed reactor system to provide a low sludge production treatment process. Conventional fixed bed systems are described in U.S. Patent No. 4,983,299.

The following examples are only intended to illustrate the present invention, the scope of which is considerably broader. These examples are not to be considered as limiting in any way.

EXAMPLES example 1 Comparison of carbon impregnated foams in fixed bed reactors

A comparison of foams impregnated with activated carbon by a number of different processes is shown in Table 1. The supports were tested by packing glass columns 64 cm high and 3.4 cm in diameter. The packed bed in Column I consisted of a flexible polyether-based polyurethane foam with a typical sponge structure and a density of 19.2 kg/m³ (1.2 lb/ft³) from General Foam Corporation, West Hazelton, PA, USA. The foam blocks were approximately 13 mm (1/2 inch) in size. The column was inoculated with 200 ml of a phenol-degrading bacterial culture. The packed bed in column II consisted of polyurethane foam as in column I, but was impregnated with activated carbon as follows: The foam blocks were immersed in 500 ml of a 1% solution of benzylpolyethyleneamine (B-PEI) in ethyl alcohol containing 100 g of activated carbon powder of Calgon type WPX. The foam blocks were removed from the impregnation bath and excess liquid was squeezed out. The blocks were then dried in a vacuum hood for 12 hours and then tumbled in a drum to remove the unbound carbon. The packed bed in column III consisted of polyurethane foam as in column I, but was impregnated with activated carbon as follows: impregnated: The foam blocks were immersed in 500 ml of a 100% solution of polystyrene in ethyl acetate containing 100 g of Calgon WPX activated carbon powder. The blocks were then dried and prepared as described above. The packed bed in column IV consisted of polyurethane foam analogous to column I, but was impregnated with activated carbon as follows: The foam blocks were immersed in 500 ml of ethyl acetate containing 100 g of Calgon activated carbon powder. The blocks were then dried and prepared as above. A wastewater feed containing 500 mg/L phenol and 10 mg/L 2,4-dimethylphenol was fed to the reactors with a hydraulic residence time of approximately 12 hours. The results are shown in Table 1 below. Table 1 Comparison of carbon impregnated foams in fixed bed reactors.

The results show that the substrates impregnated with activated carbon effectively absorb phenolic substances.

Example 2

Experiments were carried out to assess the ability of activated carbon to bond to a carrier by means of heat treatment.

. . General procedure for producing beams by heat treatment

1. Weigh a 25x25x25mm (1 inch x 1 inch x 1 inch) piece of PUS (polyurethane foam). The foam is ScottBlue Foamex (SBF) from from Foamex.

2. Add an excess of AKP, activated carbon powder from Calgon, (approximately 2 g) and SBF to a vessel, which is heated to different temperatures for different periods of time, in accordance with the information given in Table 2, while shaking.

3. Discharge the SBF from the vessel. Excess AKP was removed by shaking by hand and washing with deionized water.

AKP coverage was determined visually by observing the AKP-coated SBF under a microscope. The results are shown in Table 2. TABLE 2

A - SBF was used as supplied.

B - SBF was washed in deionized water before application of AKP.

Summary of the experiments presented in Table 2

With increasing treatment time and temperature, the AKP occupancy increased. The disadvantage of the heat treatment is the lack of a firm bond between the AKP and the PUS, although the AKP remained in an active state. During the heat treatment, AKP water is expelled. In general, temperatures of about 70 to 137ºC seem to support the binding of AKP to PUS. Shaking removes only small amounts of AKP, whereas vigorous washing with water flushes out over 60% of the AKP.

Measurements of binding activity

To evaluate a range of carrier systems, without using each of them in a bioreactor, alpha values were used to analyze the relative binding properties of the carriers produced. The alpha value for each sample is calculated using the alpha value formula mentioned above.

The alpha value can vary considerably depending on the amount of absorbent used and the initial amount of pollutant (e.g. phenol). However, the differences in alpha values for the same initial amount of phenol can be related to the relative effectiveness of the carrier in binding a pollutant. The correlation is confirmed by the results obtained in the tests in the bioreactor (ICB). The general procedure for determining the alpha value is as follows:

1. A 25x25x25 mm (1 inch x 1 inch x 1 inch) or similar sized cube or plate of the material to be tested for its ability to bind phenol was either molded as a composite or cut from a larger piece of material/composite.

2. In a 250 wide-necked Pyrex flask No. 5100 with a 100-mL Pyrex graduated cylinder No. 3022 100 mL of phenol containing 100 ppm (+/- about 2% by analysis) was placed.

3. The flask was sealed with a rubber stopper wrapped in aluminum foil. The aluminum foil is intended to prevent the rubber stopper from absorbing organic substances.

4. The material cube to be tested is added to the phenol solution and the flask is closed with the stopper and moved on an orbital shaker at 250 rpm for 24 hours.

The solutions were tested for phenol as follows:

Determination of pollutant concentration

Phenol concentration was determined using the standard analytical method using 4-aminoantipyrine (AAP), see Standard Methods for Examination of Water and Wastewater, 16th ed. (1985), Method (510-4AAP). For measurements on samples containing less than 1 ppm phenol, a separate standard curve was used for phenol concentrations between 0.25 and 1 ppm. In some examples, the amount of contaminant was determined using GC/MSD, i.e. gas chromatography analysis with selective mass detector. The GC/MSD method is both more sensitive and more selective than the 4-AAP method.

Example 3

An alpha value was calculated using the heat treatment procedure and phenol determination described above. The AKP and SBF were heated to a temperature of 100ºC for 24 hours. The results are shown in Table 3. Table 3

In the above experiment and in any experiment to determine the alpha value, the solvent is water and the volume is 100 ml.

Example 4 Determination of the effect of solvent on the alpha value of AKP

A 250 ml Erlenmeyer flask was charged with 1.0 g AKP and 100 ml of a special solvent and on an orbital shaker for 24 hours. The ACP was collected on filter paper and allowed to dry overnight at room temperature. Then one tenth of a gram of the treated ACP was mixed with 100 ml of a solution of 100 ppm phenol in water (phenol concentration 96.9 ppm) in a 250 ml Erlenmeyer flask and shaken on the orbital shaker at 100 rpm for 5 hours. The results of the phenol determination in the supernatant are shown in Table 4.

As can be seen from the alpha values, where a small value indicates deactivation of the AKP, the non-aromatic solvents had only an insignificant negative influence on the ability of the AKP to remove phenol from the solution. TABLE 4

Examples 5-10

The following tests and tables were obtained using the materials and procedure described here. The alpha values obtained reflect improvements in the application of the binder to a substrate or the benefit of a specific binder or solvent, as indicated.

materials

The polyurethane foams used in the tests were ScottBlue polyurethane foam from Foamex and a 13000 series foam from General Foam.

Activated carbon was purchased from Calgon.

Commercially available adhesives

Airflex 465, an aqueous emulsion of a copolymer of ethylene and vinyl acetate having a glass transition temperature Tg of -3ºC with at least about 66% solids, was purchased from Air Products and Chemicals, Inc.

Synthemul 40404-00, a polyvinyl alcohol (PVA) stabilized latex emulsion of a carboxylated acrylic polymer with a Tg of -50 to -42ºC containing 55 to 57% solids, was purchased from Reichold Chemicals.

Elvace 40722-00, a hydroxyethyl cellulose-stabilized aqueous latex emulsion of a copolymer of ethylene and vinyl acetate with a Tg of -10 to 14ºC containing 55 to 57% solids, was purchased from Reichold Chemicals.

Tylac 68219-00, a PVA stabilized aqueous latex emulsion of a copolymer of styrene and butadiene with a Tg of -25 to -11ºC containing 51 to 53% solids, was purchased from Reichold Chemicals.

Polysat EVSA, a styrene and vinyl toluene modified acrylic polymer in a xylene containing organic solvent at 50% solids, was obtained from Polysat Inc., the Tg of which was not specified by Polysat. Polysat SAE, a suspension of an aqueous emulsion of a copolymer of styrene and acrylate in AR-100 solvent at 45% solids, was also obtained from Polysat, the Tg of which was not specified.

Polymethyl methacrylate (PMMA - catalogue number 18221-4), polystyrene (MW = 45,000) and polystyrene (MW = 280,000) were all purchased from Aldrich Chemical.

In examples 5-10, the carriers were manufactured using the two-step process of applying the absorbent and the binder to the carrier. The aim is to estimate the alpha value of carriers with different binders. The alpha value for the carrier with only binder and no absorbent (AKP) is also given. In each test, PUS (polyurethane foam) SBF from Foamex was used as the foam.

General procedure for preparing supports for the determination of phenol binding using adhesives

Our "two-step" approach, in which the liquid is first applied to the substrate (PUS) and then the AKP is bound, proceeds as follows:

1. Weigh a 25x25x25 mm (1 inch x 1 inch x 1 inch) PU piece.

2. Soak in the liquid, which is a dispersion of adhesive and water in a 50:50 ratio, for 1-2 minutes.

3. Remove excess fluid first by squeezing and then by flushing with pressurized nitrogen gas for 30 seconds.

4. Allow the applied adhesive dispersion to harden for the specified period of time.

5. Add to a container with excess AKP (about 5 g) and shake vigorously for 15 minutes.

6. Shake off excess AKP.

7. Allow to air cure for 2-3 days.

8. If necessary, heat the cured PUS in the oven at 100ºC for 1 hour, as indicated.

To describe the different carriers, an abbreviated notation has been used in the tables. The sequence of abbreviations indicates the order in which the components of the carrier are added and the carrier used. For example, PUS/AF/MINUTES/AKP/ HEAT that PUS was coated with Airflex (AF) adhesive, allowed to dry for a certain number of minutes (bonding time), coated with AKP by shaking the AF-coated PUS with AKP and then heated to 100ºC for 1 hour if necessary

Example 5

In this example, the two-step procedure was used to prepare supports using a variety of commercially available adhesives listed in the Materials section above. Many of the adhesives are aqueous latex emulsions, thus eliminating the problem of possible deactivation of AKP by organic solvents. Table 5

Note: The following adhesives were used:

AF - Airflex 465,

PS = Polysat EVSA and

SY = Synthemul 40404-00.

The results given above show that substrates coated with AKP show greatly improved alpha values. Furthermore, heat treatment of the coated substrate appears to impair its performance. The Polysat adhesive probably contains aromatic solvents that impair the performance of the substrate coated with it.

Example 6

In this example, the effect of heating, washing and washing and heating a prepared support was studied using 50% Synthemul (SY) as the binder and heating the coated substrate at 115ºC for 1 hour, where indicated. The coated substrate was washed twice with deionized water for 1 hour, where indicated. The initial concentration of phenol was 98.8 ppm. The results are shown in the table below. Table 6

The above values show the significant negative effects of heating and the insignificant effect of washing the carrier systems. It should be noted that washing is done by vigorously agitating the carrier in deionized water. Heating the carrier has a significant negative effect on the alpha value of the carrier.

Example 7

In this example, the effect of using a slurry method to apply a binder was investigated.

General slurry procedure

1. Carefully weigh a 25x25x25 mm (1 inch x 1 inch x 1 inch) piece of PU.

2. Prepare a slurry by diluting the adhesive in the specified solvent (typically 50% adhesive and 50% solvent (water) by volume), stirring rapidly with a magnetic stir bar and magnetic stir plate, and adding the specified amount of ACP until the ACP is completely wetted with the diluted solvent. The suspension is not always smooth and homogeneous, i.e. aggregation will occur. Stirring is typically for 5 to 10 minutes. Where noted, a surfactant is added to reduce aggregation.

3. Saturate the AKP adhesive slurry for 1-2 minutes while squeezing to expel any trapped air.

4. Remove the cube from the slurry and then remove excess liquid first by squeezing and then pressing against the container wall. The slurry was often lumpy. Any large lumps were scraped off the sides of the cube before drying.

5. Air dry or heat in an oven at 100ºC for 2 hours (as per the respective Experiments described). With short drying times (< 1 day), the supernatant from the phenol binding assay often appeared milky, indicating incomplete drying. After drying for two or more days at room temperature, no milkiness was observed. Table 7

The deactivation of the sample with Polysat (EVSA) is due to the aromatic solvents in the commercially available adhesive.

Example 8

Here, a comparison is made between the alpha values for 4 commercially available adhesives using a slurry method. Table 8

For the above samples, 13.3% (w/v) AKP, 40% commercial adhesive in water were used, and the phenol volume was 100 mL in each case.

Example 9

Using the slurry method The effect of varying the amount of AKP and varying the concentration of the binder in the slurry was investigated. Table 9

The above results show that the activity of the absorbent carrier can be optimized by adjusting the binder concentration. As shown above, a reduction in the binder concentration from 50 to 40% causes a change in the alpha value from 5024 to 10,650.

Example 10

In this experiment, 12.0 g of polystyrene (polystyrene foam cups) were dissolved in 48 g of ethyl acetate dissolved. 8 g of AKP was added to the viscous solution, forming a slurry. No clumping occurred. To this was added a 25 mm (1 inch) cube of General Foam 12000 series, which was squeezed approximately 5 times to expel excess air. Excess liquid was removed by squeezing and pressing the cube against the beaker wall. No roller was used. In the comparative experiment, no AKP was added to the polystyrene solution. The cubes were then examined for phenol binding.

Although the composite removed some phenol from the solution (75% of the phenol was removed from the solution, giving an alpha value of 95, compared to an alpha value of 38 for comparison, see Table XIV), it does not appear to perform as well as the various carboxylated polymers in phenol removal. Table 10

Example 11

Following the procedure described in the example above, two other polystyrenes (MW = 45 and MW = 280,000) were tested as binders. The initial phenol level for each determination was approximately 100 ppm in 100 ml of water. The results are shown below:

Example 12

Polymethyl methacrylate was tested as a binder following the procedure described in the polystyrene experiments above, but with PMMA (12 g) dissolved in 48 g THF as solvent. A separate control solution was also prepared.

Example 13 Comparison of binders based on the glass transition temperature

The table below provides a compilation of Tg values for supports prepared using the indicated binders. In all cases, the support was prepared using the slurry process under fairly similar conditions. The table reports the percent ACP (in grams) and percent binder (grams of solids) on a w/v basis, with the remaining weight percent being grams (mL) of water. Although the tests were not conducted under exactly the same conditions, the results should be relatively comparable. Table 11

* - Tg not measured, only estimated.

+ - 60-93ºC is the softening temperature.

No AKP was used for the comparison samples.

Example 14

Since polystyrene is an aromatic hydrophobic polymer with a relatively high Tg, for which an alpha value of 95 was measured, another aromatic hydrophobic copolymer, namely polystyrene-butadiene copolymer, was tested as a binder to determine whether the Tg value is an important variable in achieving a desired alpha value. Thus, 12 g of reprecipitated styrene-butadiene copolymer was dissolved in 96 g of THF. 8.0 g of AKP was added to one half of this solution, resulting in a lump-free suspension. The other half of the solution was used to coat a control cube with styrene-butadiene copolymer only. The PUS cubes were treated as described in the example above. Table 12

The resulting composite bound a significant amount of phenol (alpha value 3032 versus 39 for the control). From the results it can be concluded that it is not the hydrophobicity but the Tg value of a substrate that is responsible for high alpha values.

Example 15 Comparison of carbon "coated" foams using commercially available adhesive (Synthemul)

A comparison of the biomass foam supports using different supports is shown in the table below. The supports were tested by packing glass columns each containing approximately 638 ml of liquid volume into which the support will be introduced. The column has a diameter (ID) of 12.7 cm (5 inches) and a height of 30 cm, with 2.5-12.7 cm (1-5 inches) left free at the bottom and top of the column. The column is designed so that the feed flows upwards. There is a side entry arm approximately 2 cm above the bottom of the column. The column is connected to a O₂ is fed to the column bottom at a rate of 6 liters/hour through glass frit (very coarse). A layer of 25 mm (1 inch) diameter Pall rings is placed at the column bottom above the glass frit and above the support in front of the column outlet. Each column was inoculated with approximately 200 ml of a phenol degrading culture. A synthetic waste stream containing 750 ppm phenol plus mineral salts as indicated below was fed at a hydraulic retention time (HRT) of approximately 24 hours. After 25.81 days, a 1500 ppm waste stream was then fed to the reactors for approximately 24 hours at the same HRT. The reaction was continued for a total period of at least 32 days. Feed containing 750 ppm phenol:

The supports used in the column are described below.

Reactor 1 - The carrier consists of cube-shaped pieces from the 13000 series from General Foam with a size of 12.5 to 15.9 mm (1/2 inch to 5/8 inch)

Reactor 2 - The carrier is the foam from Reactor 1, coated with activated carbon and Synthemul adhesive using the two-step process. A 76x38x13 mm (3 in. x 1.5 in. x 0.5 in.) foam sheet is immersed in a bath of Synthemul adhesive (diluted 50:50 with water). Excess liquid is removed by passing of the foam is removed through the rollers of a pasta press set at 1.02 ml. Each slab is placed in a jar containing 11.25 g of AKP. The jar is shaken (3-5 times per second for 1 hour). The slab is allowed to cure (air dry) for 3 days and then cut into cubes approximately 12.5 mm (1/2 inch) on a side (18 cubes per slab). The cubes are washed in water by vigorous shaking, which removes any loosely bound AKP. It is washed 2-3 more times and then air dried.

Reactor 3 - A slurry was prepared by (1) mixing 100.21 mL of water, 7.1 mL of Tween 80, and 22.7 g of AKP, (2) stirring the mixture for 5 minutes to produce a smooth slurry, (3) rapidly adding 145 mL of Synthermal (diluted 50:50 with water), (4) stirring for 5 minutes, (5) immersing a 76x38x13 mm (3 in. x 1.5 in. x 0.5 in.) foam board in the slurry, removing the excess as in the preparation procedure for Reactor 2, and air drying for 3 days. Cubes were then cut to approximately 12.5 mm (1/2 in.) on a side. Table 13 Comparative presentation of the results of relative shock resistance (in ppm according to GC/MSD) Table 14 Comparison of resistance to disruption of AKP-coated and uncoated General Foam 1300 Series foam during phenol degradation in the ICB

The peak of 1500 occurred after 25.81 hours and ended after 26.74 hours, maintaining the phenol concentration at 750 ppm.

Example 16 Transfer of the treatment of a chlorobenzene waste stream to the pilot plant scale

Further testing was done with a 1500 gallon (5.68 m³) reactor. Approximately 1000 gallons (3.78 m³) of the reactor is occupied by a fixed bed of a support prepared by the slurry process for reactor 3 above. A 3-inch (76 mm) cube of General Foam 13000 series foam is used. When scaled up, the same ratios of adhesive, water, AKP and Tween are used as in reactor #3 (per gram of untreated foam). The slurry-coated foam was squeezed using a standard mop bucket attachment to remove excess slurry and air cured for 2-4 days.

A chlorobenzene groundwater waste stream was treated. Station (A) in the table below represents the concentration (ppb) of the contaminants in the groundwater immediately after extraction from the soil. The groundwater is then transferred to a storage tank and then fed to the reactor. Station 1 represents the influent immediately before the bioreactor station. Station 2 represents an opening in the lower half of the reactors. Station 3 represents an opening in the upper half of the reactor and Station 4 represents the effluent concentrations determined by GC/MSD. The results are summarized below. Table 15

Example 17

This test was designed to demonstrate the problem of clumping of the ACP when the ACP is not pretreated or is pretreated with an insufficient amount of surfactant, suspended in a latex adhesive, applied to a PUS surface, and cured by air drying. The adhesive used, Synthemul 40404-00, is an anionic surfactant-stabilized carboxylated acrylic copolymer and is available from Reichold Chemicals, Inc. Dowfax 2A1 is an anionic surfactant composed of dodecyl(sulfophenoxy)benzenesulfonic acid and oxybis(dodecylbenzenesulfonic acid) disodium salt. The Dowfax materials are available from Dow Chemical. The Type C ACP was purchased from Calgon Corp.

A slurry prepared by adding 5.4 g of AKP followed by 9.6 mL of Synthemul latex adhesive to 14.4 mL of water and 1 mL of Dowfax 2A1 with vigorous stirring was quite lumpy. The lumps could not be brought into suspension. An attempt to coat a 25x25x25 mm (1 in. x 1 in. x 1 in.) cube of General Foam 13000 series foam resulted in poor penetration of the PUS cells. Large chunks (1-3 mm, some even larger) of clumped ACP were floating on the surface. Increasing the amount of water to 19.2 mL and decreasing the amount of adhesive to 4.8 mL did not improve the slurry. Refer to Experiments 2 and 3 in Table 1. Omitting the surfactant resulted in the same or even greater clumping.

Example 18

The purpose of this experiment was to demonstrate that an appropriate concentration of surfactant (Dowfax 2A1) can prevent clumping of the ACP. The surfactant concentration was determined experimentally as the concentration closest to the minimum concentration required to prevent clumping of the ACP after the adhesive was added to the surfactant-treated ACP. The criteria used were visual inspection of the suspension (no discrete particles were visible to the naked eye; the suspension was dark gray) and the final adhesive-bonded ACP-PUS composite (some clumps less than 0.2 mm in size; ideally no clumps visible to the naked eye). As can be seen in Table 16, ratios of ACP in grams to surfactant in mL of 2.7 and 3.2 (Experiments 4, 5, and 1) gave non-clumping suspensions and good, smooth coatings on the PUS. A ratio of 5.4 (tests 2 and 3), on the other hand, results in clumping of the AKP. Table 16

Glue. = adhesive

Tens. = surfactant, Dowfax 2A1

Example 19

This experiment was designed to demonstrate that the ability of the ACP to remove phenol from solution is impaired when the ACP is pretreated with Tween 80 surfactant prior to suspension in a latex adhesive, applied to a PUS surface and air-cured. This series of experiments demonstrates that Tween 80, a non-ionic surfactant, allows the ACP to be suspended in Synthemul adhesive without clumping, but impairs the phenol-binding ability. In these experiments, 76x38x25 mm (3 in. x 1.5 in. x 1 in.) panels of GENERAL FOAM 13000 Series polyurethane foam (PUS) were treated with various ACP suspensions, the excess slurry was squeezed out with rollers, and the composite was air-cured at room temperature for two days.

Table 17 shows, from left to right, the sample number, a brief summary of the method of preparation of the different samples (the order of addition of the reagents is noted from left to right), the examinations of the condition of the slurry and the final composite (the observed degree of clumping of the ACP suspension and the observed degree of clumping of the ACP on the foam surface of the final, cured composite), the final phenol concentration after the binding determination (the initial phenol concentration of the samples was 94.1 ppm), the weight of the composite used in this determination, and the alpha value calculated from these figures.

The production of suspensions for the treatment of the individual PUS panels and the investigations of the suspensions and the finished composites were carried out as follows:

1. When preparing this suspension, no surfactant was added. 30 mL of Synthemul and then 11.6 g of AKP were added to 30 mL of rapidly stirred water within one minute. The AKP clumped strongly. It can be concluded that the degree of aggregation of the AKP is unacceptable.

2. When preparing this suspension, no surfactant was added. To 30 mL of rapidly stirred water 11.6 g of AKP was added, followed by 30 mL of Synthemul.

ANNOTATION:

The order of addition is reversed compared to sample 1. The suspension clumped only slightly, but when the PUS was treated, severe clumping occurred on the PUS surface. From this, it can be concluded that the degree of aggregation is unacceptable.

3. Surfactant was used in the preparation of this and all subsequent suspensions. 4.2 g AKP was added to 36 mL of rapidly stirred water, followed by 0.9 mL Tween 80. After stirring for 5 minutes to dissolve the Tween and wet the AKP, 24 mL Synthemul was added. The suspension was non-clumping. There was also no clumping on the foam. It can be concluded that the degree of aggregation is acceptable, although the low alpha value should be noted.

4. An attempt was made to increase the amount of AKP. To 36 mL of rapidly stirred water, 10 g of AKP was added, followed by 2.0 mL of Tween 80. After stirring for 5 minutes to dissolve the Tween and wet the AKP, 24 mL of Synthemul was added. The AKP clumped heavily both in the suspension and on the foam. This led to the conclusion that the degree of aggregation was unacceptable. The alpha value was slightly higher.

5. Here the amount of AKP was reduced to 7 g, a value between that of samples 3 and 4. Although no clumping occurred, the alpha values were quite low.

6, 7 and 8. In these experiments the procedure was analogous to 4, but the Synthemul was added quickly. The aim of these experiments was to find out how much AKP could be added before the solution clumped. In number 6, 10 g of AKP resulted in clumping, in number 7, 9 g resulted in clumping, but not as severe, and in number 8, 8 g looked very good. However, the alpha values dropped in the same order.

Overall, the conclusion that can be drawn from this series of experiments is that a non-ionic surfactant maintains a suspension of the AKP in a carboxylated polyacrylate adhesive latex very well, but impairs the phenol binding properties of the AKP.

The ingredients and addition order for each sample were as follows:

1. 30 ml H₂O + 30 ml glue. / 11.6 g ACP.

2. 30 ml H₂O + 11.6 g AKP / 30 ml adhesive.

3. 36 ml H₂O + 4.2 g AKP + 0.9 ml Tween / 24 ml Glue.

4. 36 ml H₂O + 10 g AKP + 2 ml Tween / 24 ml Glue. (L)

5. 36 ml H₂O + 7 g AKP + 2 ml Tween / 24 ml Glue.

6. 36 ml H₂O + 10 g AKP + 2 ml Tween / 24 ml Glue. (S)

7. 36 ml H₂O + 9 g AKP + 2.5 ml Tween / 24 ml Glue. (S)

8. 36 ml H₂O + 8 g AKP + 2.5 ml Tween / 24 ml Glue. (S)

Adhesive = Adhesive, Synthemul; Initial phenol concentration = 94.1 ppm; (L) = Slow Synthemul addition; (S) = Fast addition. Table 17

Note: Ex. Susp. = Appearance of the suspension.

Degree of clumping = degree of clumping on PUS.

Example 20

This experiment also served to demonstrate that the ability of AKP to extract phenol from the solution is impaired when the AKP is pretreated with Tween 80 before being suspended in a latex adhesive, applied to a PUS surface and cured by air drying. The difference from Example 19 lies in the order of addition of Tween and AKP. Table 18

Adhesive = Glue

Ten. = surfactant, Tween 80

Initial phenol concentration = 104.3 ppm

The conclusions drawn from this, which are identical to those of Example 19 above, are that a non-ionic surfactant maintains a suspension of the AKP in a carboxylated polyacrylate adhesive latex very well, but impairs the phenol binding properties of the AKP.

Example 21

This experiment was designed to demonstrate that the impairment of phenol binding by AKP when AKP is pretreated with a non-ionic surfactant is of a general nature. This series of experiments extends the conclusion that non-ionic surfactants impair phenol binding. It was found that Igepal CA-897, another non-ionic surfactant, keeps AKP in suspension but impairs its phenol binding capacity. It is similar to Tween 80 in this respect.

The tests were conducted in four groups. Test "a" in each group used General Foam 13000 series foam as the substrate, while test "b" used Scott Blue Foamex. In all of these tests, ACP was added first to rapidly agitated water, followed by surfactant, then the adhesive, and finally the PUS substrate. Prior to the tests listed in the table, it was determined what was the approximate minimum amount of surfactant required for the amount of ACP used to maintain a non-clumping suspension. As can be seen from the table, all three formulations of water, ACP, surfactant, and Synthemul adhesive (with General Foam or Foamex foam as the substrate) produced low activity composites. As in the previous experiment (No. 19), the overall conclusion from this series of experiments is that a non-ionic surfactant maintains a suspension of the ACP in a carboxylated polyacrylate adhesive latex very well, but impairs the phenol binding properties of the ACP.

The ingredients and addition order for each sample were as follows:

1a. 60 ml H₂O/13.3 g AKP/8.3 ml Ige/40 ml adhesive. Foam from General Foam was used as foam.

1b. 60 ml H₂O/13.3 g AKP/8.3 ml Ige/40 ml adhesive. Foam from FOAMX was used as foam.

2a. 60 ml H₂O/22.4 g AKP/16.7 ml Ige/40 ml adhesive. Foam from General Foam was used.

2b. 60 ml H₂O/22.4 g AKP/16.7 ml Ige/40 ml adhesive. Foam from FOAMX was used as foam.

3a. 50 ml H₂O/22.35 g AKP/16.7 ml Ige/50 ml adhesive. Foam from General Foam was used.

3b. 50 ml H₂O/22.35 g AKP/16.7 ml Ige/50 ml adhesive. Foam from FOAMX was used as foam.

Adhesive = Adhesive, Synthemul; initial phenol concentration = 110.6 ppm. Table 19

Example 22

This experiment was designed to demonstrate that cationic surfactants have even more unacceptable properties than non-ionic surfactants. In these experiments, the functionality of mixed alkyltrimethylammonium bromide (ATAB) as a suspending aid was investigated. It was found that ATAB does not result in suspension of AKP in the latex adhesive, but rather causes even greater clumping of the AKP than without the addition of ATAB. The test was conducted as follows: To each of 28 mL of rapidly stirred water in three separate beakers were added, in sequence, 8.94 g of AKP (followed by stirring for 3 minutes to suspend the AKP), 0.05, 1.25, and 2.5 g of ATAB (followed by stirring for 1 minute to dissolve), and finally 12 mL of Synthemul adhesive. All three suspension tests showed severe clumping, with the test with 2.5 g ATAB resulting in virtually complete separation of the AKP from the suspension. The test with 1.25 g ATAB was continued using the material to coat a 25x25x25 mm (1 in. x 1 in. x 1 in.) cube of General Foam foam. After curing and determination, an alpha value of 758 was calculated. The initial phenol concentration was 103.8 ppm. The suspension appeared very clumpy. The final phenol concentration was 12.99 ppm, the weight of the composition was 0.9281 g and the alpha value was 753.

The overall conclusion from this series of experiments is that a cationic surfactant makes it difficult to maintain suspension (it causes clumping of the ACP) and also tends to interfere with the phenol binding by the ACP.

Example 23

The purpose of this series of experiments was to demonstrate that the only acceptable surfactant for maintaining suspension in Synthemul without unduly affecting the phenol binding capacity of the AKP is an anionic surfactant. Using the anionic surfactant Dowfax 2A1 not only eliminated the clumping of the AKP but also largely retained the phenol binding activity. The experiment was carried out as follows. The experiments were carried out in four groups. In experiment "a" of each group, General Foam 13000 series foam was used as the substrate, while experiment "b" used Scott Blue Foamex. In all of these experiments, AKP was added to rapidly stirred water first and then Surfactant, then the adhesive, and finally the PUS substrate were added. Prior to the tests shown in the table, it was determined what approximate minimum amount of surfactant was required for the amount of ACP used to maintain a non-clumping suspension. As can be seen in the table below, all four formulations of water, ACP, Dowfax surfactant, and Synthemul adhesive (with General Foam or Foamex foam as the substrate) produced composites with high activity. The General Foam foam always produces a composite with a higher alpha value than the Foamex foam because it has a higher surface area due to larger pores per inch and a resulting greater weight gain.

Excess surfactant tends to reduce the phenol binding capacity of the ACP bound to the composite. Thus, by comparing the alpha values of tests 1a and 1b with those of tests 3a and 3b, it can be seen that increasing the amount of adhesive from 6.25 to 8.34 mL in the above tests results in a reduction in the alpha value by an order of magnitude of almost 50%. This shows how important it is to use the minimum amount of surfactant required to keep the ACP in suspension. Increasing the surfactant concentration leads to a reduction in the phenol binding capacity determined by the alpha value. A similar conclusion can be drawn from comparing tests 2a and 2b with tests 4a and 4b, in which only half as much adhesive was used as in 1a, 1b, 3a and 3b. The conclusion from this series of experiments is that an anionic surfactant maintains a suspension of AKP in the carboxylated polyacrylate adhesive latex well. At first glance, the excess surfactant appears to simply interfere with the adsorption of phenol by the AKP. However, the lower weight in the final composite observed when more surfactant is used indicates that less slurry and hence less AKP is present. Thus, although the surfactant does appear to slightly impair the phenol binding properties of the AKP, this is also due to the fact that increasing the amount of surfactant reduces the amount of AKP bound to the PUS carrier. However, less AKP leads to lower phenol adsorption capacity.

The ingredients and addition order for each sample were as follows:

1a. 60 ml H₂O/22.35 g AKP/6.3 ml 2A1/40 ml adhesive. Foam from General Foam was used as foam.

1b. 60 ml H₂O/22.35 g AKP/6.3 ml 2A1/40 ml adhesive. The foam used was FOAMX foam.

2a. 80 ml H₂O/22.35 g AKP/6.3 ml 2A1/40 ml adhesive. Foam from General Foam was used.

2b. 80 ml H₂O/22.35 g AKP/6.3 ml 2A1/40 ml adhesive. Foam from FOAMX was used as foam.

3a. 60 ml H₂O/22.35 g AKP/8.3 ml 2A1/40 ml adhesive. Foam from General Foam was used.

3b. 60 ml H₂O/22.35 g AKP/8.3 ml 2A1/40 ml adhesive. The foam used was made by FOAMX.

4a. 80 ml H₂O/22.35 g AKP/8.3 ml 2A1/40 ml adhesive. General Foam was used as foam.

4b. 80 ml H₂O/22.35 g AKP/8.3 ml 2A1/40 ml adhesive. The foam used was made by FOAMX.

Adhesive = Adhesive, Synthemul; 2A1 = Surfactant Dowfax 2A1; Initial phenol concentration = 101.3 ppm. Table 20

Example 24

This experiment was designed to extend this discovery to another anionic surfactant. In this example, Dowfax 8390 was investigated. Dowfax 8390 is composed of disodium hexadecyldiphenyl oxide disulfonate and disodium dihexadecyldiphenyl oxide disulfonate. The procedure was analogous to Example 23.

When 1 and 1.5 mL of Dowfax 8390 and Dowfax 3B2 were used in the following tests, the ACP aggregated to an unacceptable extent. These composites were not tested for their phenol binding capacity.

The ingredients and addition order for each sample were as follows:

1a. 16.8 ml H₂O/5.4 g AKP/2.0 ml 8390/7.2 ml adhesive. Foam from General Foam was used as foam.

1b. 16.8 ml H₂O/5.4 g AKP/2.0 ml 8390/7.2 ml adhesive. The foam used was FOAMX foam.

2a. 16.8 ml H₂O/5.4 g AKP/2.5 ml 8390/7.2 ml adhesive. Foam from General Foam was used.

2b. 16.8 ml H₂O/5.4 g AKP/2.5 ml 8390/7.2 ml adhesive. Foam from FOAMX was used as foam.

3a. 16.8 ml H₂O/5.4 g AKP/3.0 ml 8390/7.2 ml adhesive. Foam from General Foam was used.

3b. 16.8 ml H₂O/5.4 g AKP/3.0 ml 8390/7.2 ml adhesive. The foam used was made by FOAMX.

Adhesive = Adhesive, Synthemul; 8390 = Surfactant Dowfax 8390; Initial phenol concentration = 101.5 ppm. Table 21

The conclusions drawn from this correspond to those of Example 23.

Example 25

This experiment was designed to extend this discovery to yet another anionic surfactant. In this example, Dowfax 3B2 was tested. Dowfax 3B2 is composed of disodium decyl(sulfophenoxy)benzenesulfonate and disodium oxybis(decylbenzenesulfonate). The procedure was analogous to Example 23.

When 1 or 1.5 mL of Dowfax 3B2 was used in the following test, the ACP aggregated to an unacceptable extent, as was the case with Dowfax 8390. These composites were not tested for their phenol binding capacity.

The ingredients and addition sequence for each sample were the same as in Example 24, except that Dowfax 3B2 was used instead of Dowfax 8930. Table 22

The conclusions drawn from this correspond to those of Examples 23 and 24.

Example 26

The purpose of this experiment was to determine whether it was possible to use a zwitterionic surfactant to prevent aggregation of the AKP without affecting the phenolic binding of the final composite. In this experiment, N-dodecyl-N,N-dimethyl-3-amino-1-propanesulfonate (DDAP) was investigated. This compound acts as a surfactant with both a cationic and an anionic molecular component. The procedure was analogous to Example 23. The PUS used in these tests was General Foam's 13000 series foam.

In analogy to the results of the tests with the anionic surfactants Dowfax 8390 and 3B2, respectively, it was found that the lower amounts of surfactant DDPA (1.2 and 1.5 g) did not prevent the clumping of the ACP suspensions, resulting in clumping on the surface of the PUS cubes and less PUS weight gain (see Table 23). The alpha value increased with increasing DDAP, resulting in less clumping and increased PUS weight gain. Using 1.8 g of DDAP completely eliminated clumping (see Table 23). The performance of this surfactant is not too different from that observed in Example 25 for the anionic surfactant Dowfax 3B2. However, the highest alpha value obtained (3280 with General Foam foam as substrate) is still far below the range of 10,000 to 13,000. This is probably primarily due to the lower amount of slurry bound to the PUS substrate (see the weight of the composites).

The ingredients and addition order for each sample were as follows:

1. 16.8 ml H₂O/5.4 g AKP/1.2 ml DDAP/7.2 ml adhesive.

2. 16.8 ml H₂O/5.4 g AKP/1.5 ml DDAP/7.2 ml adhesive.

3. 16.8 ml H₂O/5.4 g AKP/1.8 ml DDAP/7.2 ml adhesive.

4. 16.8 ml H₂O/5.4 g AKP/2.4 ml DDAP/7.2 ml adhesive.

Adhesive = Adhesive, Synthemul; DDAP = surfactant N-dodecyl- N,N-dimethyl-3-amino-1-propanesulfonate; initial phenol concentration = 96.6 ppm. Table 23

Example 27

The purpose of this test was to determine whether a straight-chain alkyl sulfonate surfactant would have similar properties to the other anionic surfactants in preventing clumping and not affecting too much the phenol binding activity of the final AKP composite. In this example, General Foam foam was used because applying slurry to this small-pore foam makes clumping of the AKP easier to detect than when using a large-pore foam such as Scott Blue Foamex. The slurry is prepared and applied to the PUS as described above. The surfactant solution (9 g SDS, diluted to 100 with deionized water) was first added to the water. mL), then the ACP, and finally Synthemul adhesive (55 to 57% solids) were added. As can be seen from the table below, all SDS concentrations resulted in moderate clumping of the ACP in the suspension and severe clumping of the ACP on the surface of the General Foam foam cubes. The SDS appears to interfere with the binding of phenol by the ACP, since preparation of the composite from slurries with decreasing amounts of surfactant produced composites with higher activity. That is, the composite prepared with the lowest surfactant concentration had an alpha value four times that of the composite prepared with three times the surfactant concentration. It can be concluded that disulfonated anionic surfactants, such as Dowfax 2A1 and 3B2, work well, whereas straight chain monosulfonated surfactants do not. The reason for this is unclear. Possible reasons for the superior performance of the disulfonated surfactant include:

1. Increased charge density of two closely adjacent charged groups.

2. Higher electrolyte strength of the disulfonated surfactants compared to the monosulfonated ones.

3. The presence of an ether bridge in the disulfonated Dowfax surfactants enables better conformational adaptation and thus more intimate interactions with the target ions/target surfaces.

4. Improved stabilization of the latex particles due to more efficient latex particle coverage and higher charge density in the case of the disulfonated surfactants.

The ingredients and addition order for each sample were as follows:

1. 0 ml H₂O/16.8 ml Ten./5.4 g AKP/7.2 ml Glue.

2. 4.2 ml H₂O/12.6 ml Ten./5.4 g AKP/7.2 ml Glue.

3. 7.4 ml H₂O/9.5 ml Ten./5.4 g AKP/7.2 ml Glue.

4. 9.7 ml H₂O/7.1 ml Ten./5.4 g AKP/7.2 ml Glue.

5. 11.55 ml H₂O/5.3 ml Ten./5.4 g AKP/7.2 ml Glue.

Kleb. = Adhesive, Synthemul; Ten. = Surfactant solution of 9 g sodium dodecyl sulfate, dissolved in water and made up to a total volume of 100 ml; initial phenol concentration = 99.4 ppm. Table 24

Example 28

The tests in Example 28 concern the use of ammonium caseinate as a suspending aid. The results given below demonstrate the superior performance of carriers made with the caseinate.

An ammonium caseinate solution was prepared as follows. To 200 mL of rapidly stirred deionized water were added first 5 g of hydrochloric acid casein type HC-200 (National Casein Co., Chicago, Il., USA) and then 1 mL of an ammonium hydroxide solution prepared by filling 68.49 mL of 29.2 wt.% (spec. D. 0.899) ammonia water to 100 mL with deionized water. This solution was prepared within about 0.5 h.

Slurries containing the ammonium caseinate as a suspending aid were prepared as follows. To 25 mL 12.5 g of AKP were added to a stirred solution of the ammonium caseinate solution. Stirring was continued for a few minutes until a smooth suspension was obtained. This stirred mixture was first mixed with 6.25 g of Synthemul 40404 latex adhesive (or Hycar) and then with 11.75 ml of water and the suspension was stirred for a further 15 minutes.

Slurries containing Dowfax 2A1 as a suspension aid were prepared analogously.

In all of the tests below, a 25 x 25 x 25 mm (1 in. x 1 in. x 1 in.) cube of General Foam 13000 Series foam was compressed in the agitated slurry to expel air and then passed through two rollers set 2.11 mm apart to squeeze out excess slurry.

The results of the following tests are summarized in the attached table.

Experiment #1 was designed to demonstrate that an active, stable composite can be obtained by first air drying a cube of slurry coated PUS and then heating it to a temperature of 150ºC without deleterious effects. The slurry coated PUS was prepared using ammonium caseinate, Hycar and AKP Type C as described above. The sample was then allowed to air dry for 18 hours and then heated to 150ºC for 10 minutes immediately prior to phenol binding determination. The resulting composite showed excellent binding properties and appeared to be quite stable in water. The alpha value obtained for this composite is the highest value obtained anywhere. Curing at 150ºC has no deleterious effects on the binding activity of the composite.

Experiment No. 3 was designed to demonstrate that heating an air-dried composite to 150ºC is not absolutely necessary and can be replaced by air-drying at ambient temperature (about 22ºC).

This sample was prepared in the same way as #1, except that the slurry-coated PUS cube was air dried for 48 hours and then dried in a vacuum oven at 30°C for 18 hours. The resulting composite had excellent phenol binding properties and appeared to be quite stable in water. The alpha value obtained from the phenol determination was largely consistent with that of Experiment #1. It should be noted that the vacuum oven drying is not essential to the practice of the present invention and is only used to drive off moisture to obtain an accurate dry weight of the sample. Other preparations that were not vacuum dried had essentially the same properties as those that were only air dried (for more than 48 hours).

Runs 5, 6 and 7 were designed to demonstrate that heating the slurry to 150ºC as the sole curing step is not sufficient to adequately cure the slurry coated PUS as evidenced by the lack of resistance to peeling in an aqueous system. Slurry coated PUS cubes were prepared as described above. For Run 5, a freshly coated cube was placed in an oven set at 150ºC and cured for 10 min. After removal from the oven, it was cooled to room temperature (approximately one minute) and then placed in the phenolic binding solution. When determined, the phenolic solution was very milky with much of the ACP in the supernatant. This clearly indicates insufficient cure time resulting in poor adhesion between the latex adhesive and ACP. Experiment 6 was the same as Experiment 5, except that the slurry-coated PUS cube was allowed to air dry for 24 hours after heating but before determination. Experiment 7 was the same as Experiment 5, except that the slurry-coated PUS cube was air dried for 24 hours before heating for 10 minutes. In the last two experiments, the The resulting composites exhibited excellent phenol binding properties and appeared to be quite stable in water. The alpha values obtained from the phenol determinations largely correspond to those obtained in Experiment 1.

Test 8 was used to show that the latex adhesive Synthemul 40404 can be used instead of the Hycar adhesive used in test 2. Otherwise, the composite was prepared in the same way as in test 2. The resulting composite had excellent phenol binding properties and appeared to be quite stable in water. The alpha value obtained from the phenol determination largely corresponds to that obtained in test 1.

Experiment 9 was similar to Experiment 8 to demonstrate that the latex adhesive Synthemul 40404 could be used instead of the Hycar adhesive used in Experiment 3. Otherwise, the composite was prepared in the same way as in Experiment 3. The resulting composite had excellent phenol binding properties and appeared to be quite stable in water. The alpha value obtained from the phenol determination was largely the same as that obtained in Experiment 1. Experiments 11 and 12 were the same as Experiments 1 and 6, but with the modification that the casein was replaced by Dowfax 2A1. Although the resulting composite appeared to be quite stable in water, the alpha value obtained from the phenol determination was lower than that obtained using casein as a suspending aid. Table 25

DRYING METHODS:

A. 18 H AIR DRYING + 10 MIN. 150ºC OVEN

B. 48 H AIR DRYING + 18 H 30ºC VACUUM OVEN

C. 10 MIN. 150C OVEN

D. 10 MIN. 150C OVEN + 24 H AIR DRY

ADHESIVE =GLUE, IE HYCAR MEANS HYCAR 2671 OF THE COMPANY BF GOODRICH; SYNTH MEANS SYNTHEMUL 40404-00 OF THE REICHOLD CHEMICAL COMPANY.

* AMM.CASE. = AMMONIUM CASEINATE; ** DOWFAX = SURFACTANT DOWFAX 2A1

ANNOTATION:

DURING THE BINDING DETERMINATION, GLUE & ACP WERE RELEASED INTO THE SUPERNATNANT, THIS WAS NOT OCCURRED IN ANY OF THE OTHER SAMPLES.

DETERMINATION VOLUME = 100 mls.

Claims (10)

1. A process for purifying an aqueous feed stream containing pollutants, in which the feed stream is passed through a bioreactor in the presence of a gas containing an effective amount of oxygen, the bioreactor containing a biologically active carrier containing: (a) a coated carrier made of a substrate with a coating composition applied thereto at least in places, containing (i) at least one particulate absorbent which absorbs and then releases the pollutants, (ii) at least one binder binding the absorbent to the surface of the substrate with a Tg below 100°C, and optionally (iii) a zwitterionic or anionic suspending aid, the suspending aid having anionic functionalities selected from the group consisting of sulfonate, sulfate, sulfite, phosphate, phosphite, phosphonate, carboxylate and combinations thereof, and (b) one or more pollutant-degrading microorganisms adhered to the surface of the coated carrier, contains. 2. The process of claim 1, wherein a binder having a Tg less than or equal to about 50°C is used. 3. The process of claim 1, wherein a binder having a Tg less than or equal to about 25°C is used. 4. The method of claim 1, wherein the absorbent is selected from the group consisting of carbon, soot, activated carbon, silica gel and activated clays. 5. A process for the preparation of a biologically active carrier for use in a reactor for the biological treatment of contaminated waste streams, which comprises: (a) applying a binder to the surface of a substrate, (b) applying one or more particulate absorbents to the binder, (c) allowing the binder to harden and (d) adhering one or more microorganisms to the surface of the coated support, the binder binding the absorbent to the surface of the substrate and having a Tg below 100ºC, the absorbents being capable of absorbing the contaminants and the microorganisms being capable of degrading the contaminants. 6. A process for the preparation of a biologically active carrier for use in a reactor for the biological treatment of contaminated waste streams, which comprises: (a) preparing a slurry containing at least a binder, one or more particulate absorbents, a zwitterionic or anionic suspending aid and a non-aromatic solvent, (b) applying the slurry to the surface of a substrate to form a coated carrier, (c) allowing the coated carrier to dry and (d) adhering one or more microorganisms to the surface of the coated carrier, wherein the binder binds the absorbent to the surface of the substrate and has a Tg below 100°C, the absorbents are capable of absorbing the contaminants, the suspending aid has anionic functionalities selected from the group consisting of sulfonate, sulfate, sulfite, phosphate, phosphite, phosphonate, carboxylate and combinations thereof, and the microorganisms are capable of degrading the contaminants. 7. Biologically active carrier for removing contaminants from a fluid stream, comprising: (a) a coated carrier comprising a substrate having applied thereto at least in places a coating composition comprising (i) at least one particulate absorbent which absorbs the pollutants absorbed and then released again; (ii) at least one binder binding the absorbent to the surface of the substrate with a Tg below 100ºC and optionally (iii) a zwitterionic or anionic suspending aid, wherein the suspending aid has anionic functionalities selected from the group consisting of sulfonate, sulfate, sulfite, phosphate, phosphite, phosphonate, carboxylate and combinations thereof, and (b) one or more pollutant-degrading microorganisms adhered to the surface of the coated carrier. 8. A biologically active carrier according to claim 7, wherein the suspending aid is zwitterionic and has a negative net charge. 9. A biologically active carrier according to claim 7, wherein the suspending aid is selected from the group consisting of dianionic and polyanionic organic compounds. 10. A biologically active carrier according to claim 7, wherein the suspending aid is a salt of a compound or polymer of the following formulas: X-R-X (1) ( )n (2) (-R- -)n (3) where X is a functional group that imparts a negative net charge to the substance according to the formula, R is a hydrocarbon such as an aromatic, heteroaromatic, cycloaliphatic, aliphatic, including heteroatom-containing hydrocarbon, as well as a peptide or a protein or a polymeric form one of these groups means U represents a heteroatom, where the valences not saturated by bonds with R or X are saturated with H, OH, halogen or an alkyl or alkoxy radical with 1-8 carbons, and n such an integer means that the number of carbons in the suspension aid is 1 to about 50.